The present invention relates to an angle-of-rotation sensor that includes at least the following elements:
(1) a rotor unit positioned on shaft for rotation about an axis;
(2) a stator unit disposed on the rotational axis and having at least one sensor element which creates a signal that corresponds to the rotational position of the rotor unit with respect to the stator unit;
(3) a stamped lead assembly at least partially imbedded in insulating material comprising at least one lead line by means of which the signal is passed to an output unit; and
(4) at least one circuit component connected to the lead assembly.
A device of this type is known from EP-A-1 054 237 which corresponds to DE-U-20 002 719, DE-U-20 003512 and U.S. patent application Ser. Nos. 09/702,342 and 09/788,630.
Two Hall sensors are arranged in a gap recess between stator elements of the stator unit. The rotor unit with a magnet is free to move within an air gap with respect to the stator unit. The stator and rotor units are at least partially surrounded by a housing body. The housing body includes a plug unit with plug contacts. The Hall sensors are connected to the plug contacts of the plug unit via a stamped lead assembly (lead frame). Components are mounted on the lead frame, which consists of several lead lines. When the housing body is formed, the lead frame and the components are at least partially incorporated into the housing parts consisting of plastic.
Installation of the individual parts of the angle-of-rotation sensor has turned out to be difficult. Also, the stamped lead assembly and the parts of the housing in which the lead assembly is embedded possess different coefficients of expansion. When such a device is installed in the engine compartment of an automobile, the Hall sensors may be displaced because of the prevailing temperatures of from minus 40xc2x0 C. to 140xc2x0 C., with results ranging from measurement inaccuracy and materials expansion problems to cracking of the stamped lead assembly and/or the housing body.
An angle-of-rotation sensor is also known from the International Patent Publication No. WO-A-9 514 911. It consists of a stationary part and a rotating part. The stationary part comprises two half-moon-shaped stator elements between which a gap is located. A Hall sensor is located in the gap. The rotating part includes a ring-shaped magnet that is held in place by a bracket and is free to move around the stator elements within the gap.
This angle-of-rotation sensor has proven itself, but its installation is relatively expensive.
The principal object of the invention is therefore to develop an angle-of-rotation sensor of the above-mentioned type to the extent that its installation is simplified, and that the temperature variations may be managed without device destruction.or function impairment.
This object is achieved by the invention wherein the stamped lead assembly is at least partially embedded in a shaped holding bracket by means of which, forming a holder unit, the stator unit is held together with the sensor element and the output unit, and wherein an expansion unit is positioned at least within the lead lines of the stamped lead assembly and at least partially in the shaped holding bracket.
The advantages realized by the invention result primarily from the fact that the expansion unit positioned in the bracket between the stator elements and the output unit allows compensation for the variations in expansion between the lead lines made of metal and the holding bracket made of plastic. A further advantage is the fact that the sensor element is already combined with the output unit and that the stator unit is combined with the sensor element and the output unit as an assembled piece by the holding unit. This allows reduction of installation costs during assembly of the position sensor device. Also, the main parts of the position sensor device are pre-adjusted, and require no further adjustment after installation.
At least one electronic component may be embedded into the shaped holding bracket. The stator unit may be held together by the shaped holding bracket with the sensor element and the output unit as described above.
The shaped holding bracket, as mentioned above, may be manufactured from insulating material. It is also possible to manufacture the shaped holding bracket of metal, whereby the stamped lead assembly is insulated by the insulation within the metal holding bracket.
Each sensor element may include at least one connection element that is connected with the lead lines of the stamped lead assembly. At least one additional component may be connected to at least one connection element. Production costs may be reduced by positioning components directly onto the connection elements of the sensor elements. The electronic components may be checked before installation by the sensor elements. If the components or the sensor element itself is defective, only one part of the position sensor device need be replaced.
At least one conductor expansion notch may be included in the connection element. The manner of installation of line conductor expansion notches depends, of course, on the design of the connection line elements. Additional components may be soldered to two adjacent connection line elements. This allows the use of inexpensive connection equipment.
The components and additional components may be arranged parallel or offset to one another on the lead lines and on the connection line elements. The electronic components and additional components may be separate or mounted on a printed circuit board. The manner of arrangement of components and/or printed circuit boards with one or more components depends on the particular requirements or possibilities.
The expansion unit may take various forms.
A first embodiment of an expansion unit includes an expansion arch arranged within the stamped lead assembly and a shaped holding bracket expansion arch in the shaped holding bracket compatible with it. An expansion arch used here, as known from tubing construction, is completely included into the holding bracket. This expansion arch may be semi-circular, U-shaped, xcexa9-shaped, or similar. Such an expansion arch compensates for all length alterations of the stamped leads and the shaped holding bracket of the holder unit surrounding it. It is distinguished by its simplicity and by a high resistance to external influences such as dirt and moisture.
A second embodiment of an expansion unit is shaped more suitably. For it, a lead window is included in the shaped holding bracket that exposes the individual leads in this area. The lead window may be limited by at least one shaped holding strap. The expansion notches in the leads accept material shrinkage or expansion. In the area of the expansion notches, the leads may deform laterally or upwards during material expansion. During shrinkage processes, on the other hand, the material of the leads is stretched in the area of the lead recesses. Plastic is more flexible than metal in elongation or compression. That is why the straight shaped holding strap of the grid window can accept slight elongations or separations.
So that the material alterations need not be compensated only by materials properties, the shaped holding bracket or the exposed lead lines may be more expansion-intensive. A shaped expansion arch may be used here. The shaped expansion arch easily compensates for all materials alterations that may result from the broad range of temperatures between minus 40xc2x0 C. and 140xc2x0 C. occurring in the engine compartment of an automobile.
For a third embodiment of an expansion unit, two expansion units of the second type are arranged one after the other.
The expansion arcs may be bent either upwards or downwards in the second and the third expansion unit with respect to the lead lines of the lead assembly that run straight through them.
A stepped expansion piece may be positioned between the first and the second lead window of the third expansion unit. This allows the third expansion unit to act, in part, as a fourth expansion unit.
The stator unit may comprise two stator elements that are arranged together by means of at least one separation recess. At least one Hall sensor may be arranged in one of the separation recesses as a sensor element. The rotor unit may consist of at least one magnet segment that is positioned on the shaft. The shaped holding bracket may be so positioned within a housing body so that it is perpendicular to the rotor axis, that the stator segments are arranged facing the magnet across an air gap, and so that the output unit is properly arranged within the housing. Thus, the position sensor device is installed using only a few hand motions. The entire installation is thus reduced to a few hand motions because the main parts are already properly installed and positioned. The output unit may consist of a plug unit and a drive unit. The plug unit may be properly positioned within a plug recess in the housing body. The drive unit may be properly installed by placing it in a drive housing of the housing body.
The connection line elements may be at least partially bent along a curved line. Two Hall sensors are provided. These Hall sensors are bent at about a 90xc2x0 angle from the curved line so that they may be positioned properly and accurately in the gap recesses between the two stator elements. The various embodiment options of the expansion unit ensure that the two Hall-sensors always remain in the proper position in the gap recesses. Thus, accurate measurement value determination of the rotation of the rotor unit with respect to the stator unit is possible.